Optical switching by saturation-induced phase changes in an active directional coupler

Abstract

The refractive index in a traveling-wave semiconductor waveguide amplifier changes with light injection at intensities close to the saturation intensity due to light-induced changes in the carrier density. The saturation-induced optical switching in an active directional coupler switch based on this effect is investigated. The system can switch from a cross state at a low input power to a bar state at a high input power. This device may be used as a power-limiting directional coupler switch with gain in a local area network.